So, my engine with 158k miles, smokes on startup. It used to be every 4th or 5th time, now its any time its been sitting longer than an hour. My guess is that the exhaust valve seals are gone. Is it possible or even a good idea to replace the seals with heads on the engine? I know that this is possible in other engines. Compression is even across at about 170 plus/minus 5. Anyone done just a value job with an engine this old? Or is this a slippery slope to a full engine rebuild? The engine runs strong and burns a quart every 1500-2000 miles, which I don't mind.